Amperometric detection of ascorbic acid in honey using ascorbate oxidase immobilised on amberlite IRA-743
2012
da Silva, Vanézia Liane | Cerqueira, Marcos Rodrigues Facchini | Lowinsohn, Denise | Matos, Maria Auxiliadora Costa | Matos, Renato Camargo
A differential amperometric method for the specific determination of ascorbic acid in honey was developed by association of a flow injection analysis (FIA) system and a tubular reactor containing the ascorbate oxidase enzyme immobilised. A gold electrode modified by electrochemical deposition of palladium was employed as working electrode. Ascorbic acid was quantified in seven samples of commercial honeys using a potential of +0.60V vs. Ag/AgCl₍ₛₐₜ₎. The linear dynamic range in ascorbic acid extends from 1 to 50μmolL⁻¹, at pH 7.0. At flow rate of 1.5mLmin⁻¹ and injecting 250μL sample volumes, a sampling frequency of 180 determinations per hour is afforded. The detection and quantification limit of this method are 0.14 and 0.49μmolL⁻¹, respectively. The samples analyses were compared with the volumetric method, and showed an excellent correlation between the methods.
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